Looking for a main dish that can be eaten off our laps

Tacos are a favorite when having people over since everyone can customize according to various dietary concerns and spice levels. And they’re great since most components can be made in advance! You can make some “fancy” toppings and homemade salsa to make them more dinner party worthy

Ina's Roasted Shrimp Risotto....she has wonderful Risotto recipes that can be eaten out of bowls.

Anything in a bowl that you can eat with a spoon...no fussing with knives and forks.
E.g. grain base and protein top
Short pasta with meaty sauce
Polenta with osso buco
Basmati rice with chicken curry
Rice and beans

Ha, I'm very familiar with this situation too. What I usually do when I inevitably invite over more people for dinner than I have seats is use table space to set out a lot of finger foods, and then make one main dish that, as you said, can be eaten easily in one dish with one utensil. Last time I set out gougeres, fruits, cheese/charcuterie, some vegetarian spreads, and crackers. Then for the main dish I made a hearty salad (this one actually: https://food52.com/recipes/68152-sauteed-dates-with-roasted-butternut-squash-wheatberries-and-blue-cheese). This way we all got a chance to relax, catch up, and nibble before dinner. Initially I was worried this would be too light, but people were absolutely stuffed.

I really like salad mains for this kind of gathering, but you could also do something else that's easily combined into a balanced meal like grain bowls, mac 'n cheese or other pasta that doesn't require your guests to hold multiple utensils and balance their plates, stews or curry (hopefully less potential for spills than soup), sandwiches, etc.